DISABLING THE HL2 PA

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Probir

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Jun 3, 2020, 4:36:51 AM6/3/20
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Enable or Disable the PA
The Hermes-Lite 2.0 PA can be disabled. Transmit out is then via the low power RF1 connector with maximum power of 17dBm. The TR switch can also be disabled. This allows for full-duplex interfacing to a transverter.
---------------------------
 
Couple of points I wish to understand – if any one can revert back
1. How I can disable the PA
2. AS mentioned 17dbm can be the max. power out through RFI Connector – HOW THAT’S POSSIBLE as 17 dbm is 50WATT
 
 
73
PROBIR
VU2BQF

si...@sdr-radio.com

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Jun 3, 2020, 5:31:14 AM6/3/20
to Probir, herme...@googlegroups.com

Hi,

 

  1. PA is disabled via software
  2. 17dBm is 5 watts

 

Simon Brown, G4ELI

https://www.sdr-radio.com

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Matthew

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Jun 3, 2020, 5:34:18 AM6/3/20
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Could I recommend a quick look at this?


73 Matthew M5EVT.

si...@sdr-radio.com

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Jun 3, 2020, 5:47:13 AM6/3/20
to Matthew, Hermes-Lite

Darn,

 

I need new glasses!

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

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Probir

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Jun 3, 2020, 6:26:11 AM6/3/20
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Extremely sorry – typo on 50 watt  - THANKS Simon and MATHEW
 
73
PROBIR
VU2BQF
.........................................

Karl Heinz Kremer

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Jun 3, 2020, 6:48:52 AM6/3/20
to si...@sdr-radio.com, Matthew, Hermes-Lite
17dBm is 50mW or 0.05W - for 5W output, you need the PA, that’s why it’s there :) 5W would be 37dBm. 

de K5KHK 

Karl Heinz Kremer
PDF Acrobatics Without a Net 
PDF Software Development, Training and More... 

On Jun 3, 2020, at 5:47 AM, si...@sdr-radio.com wrote:



Amogh Desai

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Jun 3, 2020, 7:22:47 AM6/3/20
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Hi,

Whats the lowest output of the HL2 PA ?  In SparkSDR Slider range is from 0-255. Has anyone measured the actual power per setting?

Amogh
VU3DES

On Wednesday, June 3, 2020 at 4:18:52 PM UTC+5:30, Karl Heinz Kremer wrote:
17dBm is 50mW or 0.05W - for 5W output, you need the PA, that’s why it’s there :) 5W would be 37dBm. 

de K5KHK 

Karl Heinz Kremer
PDF Acrobatics Without a Net 
PDF Software Development, Training and More... 

On Jun 3, 2020, at 5:47 AM, si...@sdr-radio.com wrote:



Darn,

 

I need new glasses!

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: herme...@googlegroups.com <herme...@googlegroups.com> On Behalf Of Matthew
Sent: 03 June 2020 10:34
To: Hermes-Lite <herme...@googlegroups.com>
Subject: Re: DISABLING THE HL2 PA

 

Could I recommend a quick look at this?

 

 

73 Matthew M5EVT.

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si...@sdr-radio.com

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Jun 3, 2020, 7:55:20 AM6/3/20
to Amogh Desai, Hermes-Lite

Well,

 

The lowest output is 0 😊 . In CW with the PA output level at minimum I see ~ 1 watt. Obviously with SSB you can reduce this further.

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

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si...@sdr-radio.com

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Jun 3, 2020, 7:55:45 AM6/3/20
to Karl Heinz Kremer, Matthew, Hermes-Lite

I know 😊 .

 

I have very annoying floaters in my eyes, and at times the little sods sit right in front of the screen, just where I’m typing.

 

https://en.wikipedia.org/wiki/Floater

 

Simon Brown, G4ELI

https://www.sdr-radio.com

 

From: Karl Heinz Kremer <k...@khk.net>
Sent: 03 June 2020 11:49
To: si...@sdr-radio.com
Cc: Matthew <bal...@gmail.com>; Hermes-Lite <herme...@googlegroups.com>
Subject: Re: DISABLING THE HL2 PA

 

17dBm is 50mW or 0.05W - for 5W output, you need the PA, that’s why it’s there :) 5W would be 37dBm. 

Alan Hopper

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Jun 3, 2020, 8:16:45 AM6/3/20
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Hi Amogh,
Old versions of Spark had a minimum output of max -7.5db, this is because that is what the drive control of the dac does in 0.5db steps. The very recent releases extend this by reducing the iq signal sent to the radio this drops to max-25.5db in 0.1db steps with a special case for zero where the output is reduced to zero. I'm not sure what other sw does.  I would guess PowerSDR does what Spark use to .  
73 Alan M0NNB

Alex Pressl

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Jun 3, 2020, 3:25:28 PM6/3/20
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I use this as a handy dBm tool when working with oscilloscope and dont get lost.

Steve Haynal

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Jun 5, 2020, 1:28:22 AM6/5/20
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Hi Group,

Just a reminder that hardware control of output power by actual changes to electrical gain within the AD9866 part are limited to 7.5dB. So for the main output with PA you have ~30 to 37 dBm, and with the low power ~10 to 17 dBm. Signal strength variation beyond this may be done in software by further varying the amplitude of the signal sent to the HL2 but this at the (small) expense of some DAC bits. It is also possible to increase the power output slighly or decrease it by altering the value of R55. See the OPA2677 datasheet for details.

73,

Steve
kf7o
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